[x, y, z] = sphere(50);
surf(x, y, z), hold on   % 绘制单位球面
x1 = 0.3 * x + 0.9;
y1 = 0.3 * y - 0.8;
z1 = 0.3 * z + 0.6;
surf(x1, y1, z1)        % 绘制小一些的球面